Rotary milling-cutter.



\No. 654.436. Patented luly 24, 1900.

F. A BURNH'AM. f ROTARY MILLING TER.

(Application filed Feb. 900.)

(No Model.)

INNENTUF W AMW W W W7 wbiuf AIIY THE NQRR S PETERS C0 PNQYD UTHOWASHINGTON D C ATIEEI'.

FRANK A. BURNHAM, OF CLEVELAND, OHIO, ASSIGNOR TO THE CHANDLER &

; Miran STATESY PATENT OFFICE.

PRICE COMPANY, OF SAME PLACE.

RQTARY MiLLrNG- eUTTER;

SPECIFICATION forming part of Letters Patent1\'ro. 654,436, dated Julya, 1966. Applibation filed February 15,1900. Serial No. 5,2 68. on)model.)

To all whom it ma concern..-

Be it known that I, FRANK A. BUBNHAM, a citizen of the United States,residin g at Cleveland, in the county of Cuyahoga and State of Ohio,have invented certain new and useful Improvements in RotaryMilling-Cuttersg and I do declare that the following is afull, clear,and exact description of the invention,which will enable others skilledin the art to which it appertains to make and use the same.

My invention relates to improvements in what are known asmilling-cutters, the

same being constructed and operating substantially as shown anddescribed.

In the accompanying drawings,- Figure 1 is a plan view of a form ofcutter-head embodying my invention. Fig. 2 is a sectional elevation online 2 2, Fig. 1. Fig. 3 is a crosssection of a part of the cutter-headon a line corresponding to line 3 3, Fig. 2. Fig. i is a detail of oneof the segments for securing the cutters in the head.

Hitherto in this class of machine, so far as I am aware, it has been theinvariable practice to dispose the tools radially from the center of thehead at right angles to its axis, and the tools themselves have beenplain and straight, with their endssquare and forming cutters of theiredges. The cutting was therefore across the end, or rather by one edgeof the end, of the tool, and of course the whole tendency and effect ofthis was to more or less quickly dull that particular edge and to roundthe leading edge which first entered the land, thus soon leaving thetool dull and ineflicient. Frequent sharpening was therefore necessary,and to accomplish this one of two ways was open, either to grind off theentire end of the tool square across the full depth of the rounding orto divide the grinding between the end and the full length of theaffected. side of the tool. If the latter was done, the tool was eachtime narrowed by that much, as well as shortened, while if the end onlywas cut away it was soon so shortened as to be worthless. Either way,therefore,was objectionable, and yet there was no escape from thispractice. Hence the keeping in order of the old style of tools was bothexpensive and laborious, as must now be obvious.

The present invention is designed to be remedial in a very large measureof these sev eral objections and to present what I claim tobe a muchmore practical, economical, and advantageous construction. To these endsI employ a cutter-head-A, which in cross-section is in a sensedish-shaped or what may be termed concave-convex, having what really isa rim or outer portion a, curved laterally and outwardly uniformly allaround, so that a radial line centrally from the hub at right angles toits axis will about intersect the back edge of the rim, as denoted byline 4 4, Fig. 2. 'However, the outer edge a or periphery of the head orrim is shown here as parallel with its axis, and there is also a rearbolts B and an inclined inner face portion or seat a for each tool Catan inclination to the axis of the head of about thirty degrees to aright-angled line, as 4: l. This inclination of tool C expresses therelative inclination of what is termed the rim or dished portion of thehead. This term rim is, however, a somewhat arbitrary term, serving thepurposes of this description, but, in fact, involving also what is apart at least of the essential body of the head. Hence the tools C arepractically in direct line With the inclination of the so-callec rim andare seated in open slots having the lander ribs a of slightly-less depththan said tools between them and forming walls within which the toolsare closely engaged laterally. The said tools are furthermore held orengaged by segments D on their inner sides, adapted each to half-wayoverlap a single tool at each side, so that there are as many segmentsas tools and one segment for each tool, though each segment engages twotools, and a single bolt B for each segment. The said segments arethreaded, so that they serve as nuts for the bolts; but separate nutsmight be used on their outside, and their bearing on both sides or edgesis exclusively upon the tools and not on the land or ribs between them.This makes separate fixtures for each tool, practically, for removal oradjustment, and as a feature for lengthwise adjustment and abutment eachtool is also provided with a set-screw E in its the same inclination asthat sustained by the face portion a for the heads of the lockingrearthreaded into the body of the head at tool itself. The endwise thrust orpressure upon the tool is, therefore, against this adj ustable screwabutment, less, of course, such "grip as the segment D may afford. Theadvantage of this construction and arrangement of parts will now appearmore clearly as We consider the tool itself. The said tool issubstantially square in cross-section from end to end and presumably ofthe usual length; but instead a right-angled cutting edge, as before, itis fashioned with two beveled surfaces, forming together substantially aV shape to the cutting end, but with the lower bevel c, lying in aparallel plane with the axis of the head A, so that this furnishes thereal cutting edge or portion of the tool. The bevel c is preferably moreacute than bevel o and is what may be regarded as a sharpening-bevel.This construction slightly reduces the full cutting width of the tool ascompared with i the width of the tool above, but not much,

and it has this further advantage, that this Width can be maintainedthrough all the sharpenings of the tool to the end,because theinclination of the bevels to the tool are such as to make this possible.Furthermore, when sharpening occurs it is only necessary to dress downthe bevels to take out dullness and rounding of the edges, and this canbe done by revolving the head A against the face of a grinder arrangedto act on either bevel of all the tools at once and all will besharpened at the same time and alike.

Assuming that the front edge of the tool is rounded to, say, the line WW, more or less, the grinding of the two bevels would be back to thelines G G on both bevels. Then the cutting edge will be the same againas originally, and so on after each sharpening in the same manner. Lessgrinding on bevel 0 would Widen the edge of c.

The tools as herein disposed have been described as inclined to the axisof the head A, Fig. 2, so that in this respect they are not radial,because theytraverse the radial lines from this point of view; but whenviewed in plan, Fig. 1, the said tools are radial, as are also theirslots or seats in the cutter-head.

What I claim isl. A rotatable milling-head substantially concavo-convexin cross-section with radial seats on the inner side thereof for thecutting tools inclined to the axis of the head, and tools in said seatshaving abutments at the middle of the head, substantially as described.

2. A substantially concave-convex millinghead having a series of radialslots in its outer portion inclined to the axis of the head, and cuttersin said slots having oppositely-beveled cutting ends, the outer bevelbeing parallel to the axis of the head and the inner bevel substantiallyat right angles to the outer bevel, substantially as described.

3. The cutter-head having radially-disposed and axially-inclined seatsfor tools, and tools in said seats having cutting edges across theirextremities and adj ustable abutment-s v for the said tools to take theend thrust, and clamps to hold the tools in place, substantially asdescribed.

\Vitness my hand to the foregoing specification this 10th day ofFebruary, 1900. Y FRANK A. BURNHAM.

W'itnesses:

H. T. FISHER, R. B. MosER.

